1. Field of the Invention
The present invention relates to an electronic writing medium, and more particularly, to a self-RAID (Redundant Array of Inexpensive Disks) system using a hard disk drive having a backup head and a method of writing data to, and reading data from, the hard disk drive having the backup head.
2. Description of the Related Art
With the development of electrical technology, various writing media have been introduced. Among the various writing media, hard disk drives are widely used as large-capacity writing media for high-speed and stable storage.
A hard disk drive includes a plurality of magnetic disks, and a plurality of heads, positioned over, and under, the disks. A head detects magnetic fields of a disk to write data to, or read data from, the disk.
As the capacity of hard disk drives increases, data loss that is caused when malfunction of hard disk drives occurs due to mechanical defects also increases. In an attempt to minimize data that is lost when malfunction of a hard disk drive occurs, data backup systems that backup data in another hard disk drive have been suggested. The data backup systems are referred to as Redundant Array Of Inexpensive Disks (RAID) systems and are used as large-capacity, and low-cost, storage media. Since a set of ten hard disk drives each having a capacity of 10 GB is more economical than a single large-capacity hard disk drive of 100 GB, RAID systems use a set of small-capacity hard disk drives instead of a single large-capacity hard disk drive.
FIG. 1 is a block diagram of a conventional RAID system.
As shown in FIG. 1, after a command is input to the RAID hardware, the RAID hardware controls a data-writing hard disk drive and a backup hard disk drive to perform data write, and read, operations. For example, after a write command is input to the RAID hardware, the RAID hardware writes data to the data-writing hard disk drive and the backup hard disk drive. After a read command is input to the RAID hardware, the RAID hardware reads desired data from the data-writing hard disk drive. If desired data cannot be read from the data-writing hard disk drive, the RAID hardware reads desired data stored in the backup hard disk drive. Such a RAID system uses various methods such as RAID 0, RAID 1, RAID 2, RAID 3, RAID 4, RAID 5, RAID 6, RAID 7, and the like. Thus, by implementing the RAID system as described above, it is possible to provide additional data protection to data conventionally written to only one hard disk drive. That is, even if an error occurs in one hard disk drive, it is possible to prevent data loss by reading the desired data stored in the backup hard disk drive.
However, in order to implement the RAID system, additional hardware is needed to support the operation of the RAID system shown in FIG. 1. In addition, the hard disk drives must be compatible with the additional hardware. Since a plurality of hard disk drives, such as the data-writing hard disk drive and the backup hard disk drive, are needed to implement the RAID system, costs increase.
Accordingly, there exists a need for a low-cost RAID system capable of reliably performing data backup.